surveying laboratory (1)

SURVEYING LABORATORY MANUAL

CHEBROLU ENGINEERING COLLEGE

DEPARTMENT OF CIVIL ENGINEERING

Signature of lab in -charge

CHBROLU ENGINEERING COLLEGE

Name :

Roll No:

Acadamic year:

EXPERIMENT NO: 2 Date :CHAIN TRAVERSING

AIM: To determine the area by chain surveying

Equipment: Ranging Rods, Chain or tape, offset rods, cross staff, arrows.

Formulas:Rectangular area A = b X h

Triangular area A = ½ X b X h

Trapezoidial area A = ½ X L [h1 + h2]

Procedure:

Set the two stations A and B. By ranging these two stations place the ranging rod or

intermediate, points Using intermediate points locate offsets for the ranging between A and

B. Measure the distance by rotating the off sets starting from A and B.

Join the offsets and ranging poles to get some required amount of triangles or

trapezoidal which enables to calculate given area.

Precautions:

1. Readings should be taken without parallax error.

2. Ranging, Offsetting, chaining should be done carefully.

Result: Total area occupied =


EXPERIMENT NO: 3 Date :

TO CALCULATE THE DISTANCE BETWEEN TWO IN ACCESSIBLE POINTS.

AIM: To determine the distance between two in accessible points with compass.

Equipments Used:

Tape, ranging rod, cross staff, off sets, Prismatic compass Tripod, arrows.

Theory:

1. Prismatic Compass is mainly used to take Whole Circle Bearings. The principle of

compass traversing is it contains a magnetic needle which is divided into degrees

and half degree graduations starts from N=00 S= 18O0 E = 900 W=2700.

2. But in prismatic compass we will have graduations as N=1800 S= O0 E = 2700

W=900.

3. Eye vane and object vane passes through the centre of prism. A glass cover is

provided over the compass box. Hinged mirror is provided to measure too low or too

tall objects by inclining the mirror. A brake pin is provided to stop the oscillations of

the graduated ring.

Centering:

A tripod is placed over the stations with its legs spread with a part, so that it is at a

workable height. The compass is firmed on the tripod. It is the centred over the station

where the bearings are to be taken (i.e) the centre of the compass pivot is brought exactly

above the ground station. A plumb bob is hung from the centre of compass. In case of


arrangement of work plumb bob is not provided as stone is dropped from the center and that

point is noted as the ground station

Levelling:

The compass is levelled by high judgment. This is essential so that the graduated ring

swings freely. The levelling is achieved by a ball and socket arrangement which is adjusted

till the bubbles becomes centre in both the plane levels.

Local attraction:

The magnetic needle does not point to the north when it is under the influence of the

external attractive forces in the presence of magnetic material such as iron pipes, Iron lamps,

steel structures, Iron lamps, rails cables, chain arrows, mineral deposits in ground etc. The

needle is deflected from its (ground) normal position. Hence local attraction by the magnetic

materials has disturbing influence on the magnetic needle.

Procedure:

Let P and Q are the two points and there is an obstacle between them. Now we have

to measure the distance between P and Q by compass. Select two points A and B such that

line AB is almost parallel to the line PQ and the distance between A and B is measured with a

chain.

Place the compass and station a centering and levelly with centre A. Note the readings

of AP, AQ and AB then shift the compass to stations B after centering and levelling its place

the bearing of BA, BP and BQ.


Cosine rule For ∆ PQA

PQ2 = PA2 + AQ2 – 2 PA.AQ cos(PAQ)

From ∆ APB sine rule.

AB = PA from ∆ABQ AB = AQ

Sin P Sin B SinQ SinB

Precductions:

1. Ranging rods should be ranged accurately.

2. Magnetic needle should be perfectly straight.

3. Vertical hair of the compass may not be loose. Eye vane and object vane should

be vertical. Chaining, reading, measuring, levelling and centering should be done

without parallax error.

Result:

The distance between in accessible points is ___________.



SURVEYING AN AREA BY CLOSED TRAVERSE

AIM: To survey an area by prismatic compass and plotting after adjustment.

Equipment:

Tape, ranging rod, cross staff, off sets, Prismatic compass Tripod, arrows.

Theory:

1. Prismatic Compass is mainly used to take Whole Circle Bearings. The principle of

compass traversing is it contains a magnetic needle which is divided into degrees

and half degree graduations starts from N=00 S= 18O0 E = 900 W=2700.

2. But in prismatic compass we will have graduations as N=1800 S= O0 E = 2700

W=900.

3. Eye vane and object vane passes through the centre of prism. A glass cover is

provided over the compass box. Hinged mirror is provided to measure too low or

too tall objects by inclining the mirror. A brake pin is provided to stop the

oscillations of the graduated ring.

Centering:

A tripod is placed over the station with its legs spread well apart so that it is at a

workable height. The compass is fixed on the tripod. It is then centered over the station

where the bearings are to be taken (i.e) centre of the compass pivot is brought exactly above


the ground station. If a plumb is bob is not provided a stone is dropped below the compass

and it should fall on the peg marking on the ground station.

Levelling:

The compass is levelled by the eye-judgment, this is essential so that the graduated

ring swings freely. Sometimes two plate levels at right angles are also provided to level the

instrument. The levelling is achieved by a ball and socket adjustments which is adjusted till

the bubbles concentrated in both the plate levels.

Local attraction:

The magnetic needle does not point to the magnetic north, when it is under the

influence of the external attractive forces in the presence of magnetic materials, such as iron

pipes, iron lamps, steel structures, rails cables chain, arrows, mineral deposits in the ground

etc. The needle is deflected from the normal position because of local attraction by the

magnetic materials.

Procedure:

To run a compass traverse ABCDEA, the compass is centered over the starting station

A and levelled. The ranging rod at E is sighted and the back bearing of the line EA is

measured. Then the ranging rod at B is sighted and the fore bearing of the line AB is taken.

The traverse line AB length is measured with a tape. The compass is then shifted to the

station B, centered and levelled. The back bearing of the line AB and fore bearing of the line

BC are measured and the length of traverse line BC is measured with tape. The compass is


then shifted to the C, D and E. respectively, and the processes of taking bearing and traverse

length are repeated.

Precautions:


2. Magnetic needle should be perfectly straight.

3. Vertical hair of the compass should not be loose.

4. Eye vane and object vane should be vertical.

5. Chaining, ranging, measuring, levelling and centering should be done without any

parallax error.

Result:

Surveying of an area by closed traverse is done.



PLANE TABLE BY RADIATION

AIM: To plot the given area by method of radiation by plane table.

Apparatus:

A plane table, alidade, plumbing fork or U. Frame, plumb bob, spirit level, compass,

drawing paper with a rain proof covers.

Theory:

A plane table consists of a small drawing board mounted on a tripod thus the board

can be rotated about the vertical axis and can be clamped in any position on the table and

levelled by adjusting tripod legs.

Alidade:

A plane table alidade is a straight edge with some form of straight device. It generally

consists of a metal or wooden rule with two vanes at the ends. The two vanes or sights are

hung to fold down on the rule when it is not in use. One of the vanes is provided with a

narrow slit while the other is open and carries a wire in the slit. Both the slits thus provide a

definite line of sight and passes through the object to the sighted.

Plumbing fork:


The plumbing fork is used in large scale work. It is meant for centering the table over

a point occupied by the plane table. It is meant for transferring the point on ground to the

sheet. So that the plotted point on sheet and the ground station are in the same vertical line.

Spirit level:

A small spirit level may be used for ascertaining as if the table is properly level. The

table is levelled by placing the level on the board in two positions at right angles and getting

the bubble central in both positions.

Method of Radiation:

In the method of Radiation of plane table surveying we will draw radiating lines by

sighting the ranging rods at their respective positions on ground.

In this method, a ray is drawn from the instrument station towards the point,

the distance between the instrument station and that point is measured, and the point located

by plotting to some scale the distance so measured. Evidently, the method is more suitable

when the distances are small (within a tape length) and one single instrument can control the

points to be detailed. The method has a wider scope if the distances are obtained

tacheometrically with the help of telescopic alidade.

1. Set the table at T, level it and transfer the point on ground to the sheet by, means of

plumbing fork, thus getting point t representing T. Clamp the table.


2. Keep the alidade touching t and sight to A. Draw the ray along the fiducial edge of the

alidade. Similarly, sight different points B,C,D,E etc., and draw the corresponding rays.

A pin may be kept touching the pin while sighting the points.

3. Measure TA,TB,TC, TD, TE etc., in the field and plot their distances to some scale along

the corresponding rays, thus getting a, b, c, d, e etc. Join these if needed.

Precautions:

1. Centering and levelling should be done carefully.


3. Vertical hair of the alidade may not be loose.

4. Alidade readings should be taken carefully.

5. Rotating the instrument and plotting errors should be eliminated.

6. Chaining, measuring must be done without parallax error.

Result:

The given area is plotted on plane table by radiation method.



PLANE TABLE BY INTERSECTION

AIM: To plot the given area by method of intersection by plane table.

Apparatus:

A plane table, alidade, plumbing fork or U. Frame and plumb bob, spirit level,

compass and drawing paper with a rain proof covers.

Theory:

A plane table consists of a small drawing board mounted on a tripod thus the board

can be rotated about the vertical avis and can be clamped in any position on the table and

levelled by adjusting tripod legs.

Alidade:

A plane table alidade is a straight edge with some form of straight device. It generally

consists of a metal or wooden rule with two vanes at the ends. The two vanes or sights are

hung to fold down on the rule when it is not in use. one of the vanes is provided with a

narrow slit while the other is open and carries a wire in the slit . Both the slits thus provide a

definite line of sight and passes through the object to be sighted.

Plumbing fork:

The plumbing fork is used in large scale work. Its meant centering the table over a

point occupied by the plane table. It is meant for transferring the ground on the point on the

sheet. So that the plotted point on the ground station one in the same vertical line.


Spirit level:

A small spirit level may be used for ascertaining as if the table is properly level. The

table is levelled by placing the level on the board in two positions at right angles and getting

the bubble central in both positions.

Intersection:

Intersection is resolved when the distance between the point and instrument station is

either too large or cannot be measured accurately from single station, due to some field

conditions. The location of an object is determined by sighting at the object from the two

plane table stations and drawing the rays. The intersection of rays will give the position of

the object. The distance between two instrument stations is measured and plotted on the

sheet.

The following procedure is used.

1. Select two points A and B such that the points P to be located is visible from both the

points.

2. Set up the plane table at A and level it. Plot the point a on the drawing paper to

represent the ground station A, using the plumbing fork.

3. Pivot the alidade on a and sight the ranging rod at B, and draw a ray in that direction.

Measure the distance AB and scale off the distance ab to locate the point b.

4. The alidade still pivoted on a, sight the station P which is to be located. Draw the ray

ap’ along the ruling edge of the alidade towards P.


5. Shift the plane table to B. Set it over the station B, and level it and centre it. Orient the

plane table at B by back sighting on A. when oriented, clamp the plane table.

6. Pivot the alidade on b, and sight the station P. Draw the ray bp” along P. the

intersection of the ray ap’ drawn from a and the ray bp” drawn from b gives the

position the point P.

Precautions:



3. Vertical hair of the alidade may not be loose.




Result: The given area is plotted by plane table by inter section method.


EXPERIMENT NO: 7(a) Date :

THE TWO-POINT PROBLEM

AIM: To plot the given point by two point problem by plane table surveying.

Instruments:

A plane table, alidade, plumbing fork and plumb-bob, spirit level, compass, drawing

paper with a rain proof cover.

Theory:

The two-point problem is a special case of resection to obtain the position of the station

occupied by the table, given the plotted position of two points. The two-point problem can be

stated as follows: To determine the position, s, of the station S occupied by the plane table,

given the accurately plotted positions, p and q, of two points, P and Q, visible from the

instrument station and without occupying these two stations.

Figure below shows the problem. P and Q are two survey stations which have been

surveyed earlier and their positions plotted as p and q on the sheet. S is the instrument station

(where the plane table is to be set up) and it is required to get the position of S on the sheet as

s when the table is oriented correctly, i.e., when P-Q is parallel to p-q. The following

procedure can be adopted to solve the two-point problem.


Procedure:

1. Select an auxiliary station R such that the signals at P,Q and S are clearly visible from R

and the angles formed by P,Q and S are not very acute.

2. Set up the plane table at R. Level the table. Approximately orient the table so that p-q is

nearly parallel to P-Q. Clamp the table in this position.

3. Plot the position of R on the table by sighting to P and Q. For this, keep the alidade

against p and sight the signal at P. Draw a line along the ruling edge of the alidade.

Similarly, sight the signal at Q by pivoting the alidade against q and draw a ray. The

intersection of the two rays drawn gives the position of the station occupied by the table.

Label this point r. Point r is obtained as the position of the station occupied and is

accurate to the extent the line p-q is parallel to P-Q.

4. Transfer the point r on the table to the ground as R using the plumbing fork. A peg can be

driven to locate the ground station.

5. With the alidade kept against r, sight the ranging rod or other signal at S and draw a line.

Mark the distance S by approximation or rough chaining. Point s1 is thus obtained.

6. Shift the table to S. Level and centre the table over s1. Orient the table by back sighting at

R. For this, keep the alidade against s1 and sight the signal at R by rotating the table.

Clamp the table in this position.

7. With the alidade kept against p, sight the station P and draw a ray. This ray intersects the

line r-s at s2, giving the station s. Keep the alidade against s2, sight the signal at Q, and


draw a ray. This ray will intersect the ray r-q not at q but at q’, as the orientation of the

table is only approximate.

8. p-q’ is the representation obtained of p-q due to the error in orientation. The angle q-p-q’

is the angular error in orientation.

9. To remove this error, place the alidade against p-q’ and keep a ranging a rod at a large

distance M.

10. Keep the alidade against p-q and rotate the table until the signal at M is sighted and clamp

the table. This position is the correct oriented position, with P-Q parallel to p-q.

11. Obtain the position of S by sighting P and draw a ray. Keep the alidade against q and

sight the signal at Q. The intersection of the two rays gives the true position, s, of S. The

distance of M must be large enough to correct the orientation of the table.

Precautions:



3. Cross hair of the alidade may not be loose.




Result: The given point is plotted by plane table by two point problem method.


EXPERIMENT NO: 7(b) Date :

THE THREE – POINT PROBLEM

AIM: To plot the given point by three point problem method by plane table surveying.

Instruments:

A plane table, alidade, plumbing fork and plumb-bob, spirit level, compass, drawing

paper with a rain proof cover.

Theory:

The three-point problem is also a problem of resection. The objective is to obtain the

position of the station occupied by the table after orientation. The three-point problem can be

stated as follows: Given three visible stations and their plotted positions, to plot the station

occupied by the plane table with the table correctly oriented with respect to the three points

already plotted.

The three – point problem can be solved using many methods. The following three

methods will be discussed here:

1. Tracing paper method

2. Graphical method

3. Trial and error method


Procedure:

1. Set up and level the plane table at P.

2. Place the alidade along ca, with the point a towards A. Turn the table till the station A

is bisected. Clamp the table. Center the alidade on c and sight B. draw a ray cb’ along

the fiducial edge of the alidade. The ray will not pass through b.

3. Unclamp the table. place the alidade along ac, with c towards C. Turn the table till the

station C is bisected. Clamp the table. Pivot the alidade on a and sight B. draw the ray

ad intersecting the ray cb’ at d.

4. Place the fiducial edge of the alidade along bd, turn the table until B is bisected.

Clamp the table. The table is now correctly oriented and p must lie on bd and also on

Aa and Cc

5. Centre the alidade on a and sight A. draw a ray through a intersecting the ray db

produced at p. the point p represent the instrument station P.

6. As a check , center the alidade on C and bisect C and draw a ray through C. The ray

Cc should now pass through p, if the work is correct

Precautions:



3. Cross hair of the alidade may not be loose.





Result:

The given point is plotted by plane table by three point problem method.



HEIGHT OF INSTRUMENT METHOD

AIM: To find the elevations of a given stations by height of instrument method.

Apparatus: Levelling staff, Tripod, Dumpy level.

Theory:

The process of finding height of instrument axis at differential levels and finding out

the reduced levels of the station is called the differential levelling.

Procedure:

Set up the level instrument at P (nearer to the temporary bench mark) and level the

instrument roughly with the levelling screws. Till the circular bubbles comes to the centre by

using foot screws, till the bubble is in an exact coincidence.

Focus the eye piece through the point. Direct the telescope towards the object and

focus the objective. Focus the Telescope toward the temporary bench mark and bisect the

staff correctly and take the back sight as it is and record the readings in the levelling field

book as shown in the table.

Keep the levelling staff at the intermediate stations and obtain the readings and note

down them as intermediate sights. The readings which where taken before shifting the

instrument to a new station should be noted as Foresights. Shift the instrument to a new

station and repeat the same process

Station Backsight Intermediate

sight

Foresight Height of

instrument

Reduced

level

Remarks


FORMULAE:

Height of instrument=Reduced level or Bench Mark+ Backsight

Precautions:

1. The staff should be held vertically when the reading is taken. The staff man

should be behind the staff.

2. While taking readings, always make sure that the bubble of the level is at the

centre.

3. Read the staff correctly, there should be no parallax error.

Result:

We obtained the R.L at required stations.



RISE AND FALL METHOD

AIM: To find the elevations of a given stations by rise and fall method.

Apparatus: Levelling staff, Tripod, Dumpy level.

Theory:

The process of keeping height of instrument axis at differential levels and finding out

the reduced levels of the station is called the differential levelling.

Procedure:

Set up the level instrument at P (nearer to the temporary bench mark) as shown in fig.

and level the instrument roughly with the levelling screws. Till the circular bubbles comes to

the centre by using foot screws, till the bubble is in an exact coincidence.

Focus the eye piece through the point.Telescope towards the object and focus the

objective.

Focus the Telescope toward the temporary bench mark and bisect the staff correctly

and take the back sight as it and record the readings in levelling field book as shown in the

table.

Keep the levelling staff at the intermediate stations and obtain the readings and note

down them as intermediate sights. The readings which where taken before shifting the

instrument to a new station should be noted as Foresights. Shift the instrument to a new

station and repeat the same process.


Station Backsight Intermediate

sight

Foresight Rise Fall Reduced

level

Remarks

`

Precautions:

1. The staff should be held vertically when the reading is taken. The staff man

should be behind the staff.

2. While taking readings, always make sure that the bubble of the level is at the

centre.

3. Read the staff correctly, there should be no parallax error.

Result:

We obtained the R.L at required stations.



CONTOURING

AIM: To plot the contours of a given area.

Apparatus: Dumpy level, chain, pegs, staff, tape etc.

Procedure:

Mark the boundary of a given surface. Plan and divide the area into number of small

squares or rectangles of 5 or 10 m width and mark the points. Now place the level such that

all the readings can be taken. Adjust the dumpy level with necessary temporary adjustments

such as eye piece, cross wires etc. Now place the levelling staff at BM and tabulate the B.S.

continue the procedure of taking reading at all the marked points.Now change the station

after few readings and continue the same process.

Calculate the R.L of all points. Join the points which have same R.Ls. Some R.L

points can be obtained by measuring.

i) In this process points having some R.L s are marked.

ii) Join these points with smooth curves.

Precautions:

1. Dumpy level should have no errors.

2. Staff should be held vertically.

Result: Thus we plot the contours of a given area.


PART-II

Experiment No: 6 (a) Date :TRIGONOMETRIC LEVELLING

Aim: To determine the R.L. of top of the building when the base of the building is accessible by swing transit theodolite.

Equipment:Theodolite - 1Tripod - 1Levelling staff - 1Tape - 1Arrow - 1Plumb bob - 1

Procedure:1. Set up a theodolite at a convenient distance from the object and measure the

horizontal distance between them accurately by steel or invar tape . Let this distance be ‘D’ metres.

2. Centre the theodolite over the station point exactly and level it by mean altitude Bubble and plate levels

3. The line of collimation of the theodolite is then made horizontal by adjusting the verniers of the vertical circle to read zero.

4. Loosen the lower clamp and vertical clamp and rotate the telescope in horizontal plane and vertical plane till the top of the tower is bisected. Tighten the lower clamp and vertical clamp and by means of lower tangent screws and vertical tangent screws make fine bisection.

5. Read both the verniers C and D find the mean of these two readings gives vertical angle α1

6. Now loosen the vertical clamp an bissect the bottom of object exactly with vertical tangent screw. The mean of the two readings gives the vertical angle α 2.

H1 = D tan α1H2 = D tan α2

Height of the object H1+H2 = H = D (tanα1 + tan α2)

B.M = S= D = H.I =

Precautions: 1. Graduations errors should be eliminated.2. Eccentricity of vertical axis is eliminated.3. Errors of Bisection and improper centering are also eliminated.

Result: Thus we are determining the R.L of the top of the Building when the base of the building is accessible.


Table - 1 : Trigonometric LevellingIn

stru

men

t at

Sigh

ted

to Face Left Face Right Average Vertical

AngleC D Mean Vertical Angle C D Mean Vertical Angle

0 ‘ “ 0 ‘ “ 0 ‘ “ 0 ‘ “ 0 ‘ “ 0 ‘ “ 0 ‘ “


Experiment No: 6 (b) Date :TRIGONOMETRIC LEVELLING

Aim: To determine the horizontal distance between instrument stations and object and R.L. of the top of the object where base is inaccessible.Equipments:

Theodolite - 1Tripod - 1Levelling staff - 1Tape - 1Arrow - 1Plumb bob - 1

Procedure: 1. Set up the theodolite at ‘A’ and level it and let the angle of elevation be α1. The B.S.

reading taken on B.M. be S1.2. The theodolite is moved and set up at B and the angle of elevation of α2is measured.

The B.S. reading taken on B.M be S2.

3. The difference of elevation of two instrument axis = S1 - S2

D is the horizontal distance between B and Q b is the horizontal distance between two instrument stations.

Instruments

H1 = height of the point Q above the instrument axis at ‘A’H2 = height of the point Q above the instrument axis at ‘B’Q1 = the projection of Q on the horizontal line through ‘D’Q2 = the project of Q on the horizontal line through ‘R’

When the height of theodolite at R is higher than at ‘B’.Formula:

Distance ‘D’ = (b+S cot α2) tan α2 (tan α1– tan α2)

H1 = d1 D tan α1 H2 = (b+D) tan α2

Precautions:1. Graduation errors are eliminated.2. Eccentricity of vertical axis is eliminated.3. Errors of Bisection and improper centering are also eliminated.

Result:Thus we are determining the horizontal distance between instrument stations and object and R.L. of the top of the object where base is inaccessible.


Inst

rum

ent a

t

Sigh

ted

to Face Left Face Right Average Vertical

AngleC D Mean Vertical

angle C D Mean Vertical angle

O ‘ “ O ‘ “ O ‘ “ O ‘ “ O ‘ “ O ‘ “ O ‘ “ O ‘ “ O ‘ “


Experiment No: 7 Date :

DETERMINATION OF CONSTANTS OF TACHEOMETER

Aim: Determine the multiplying constant (K) or (t/i) and additive constant (c) or (f+d) of a given Tacheometer, using field observations.

Equipment Used: Tacheometer, levelling staff, chain or tape, ranging rods.

Objective of the Experiment: Determine the multiplying constant (K) or (f/i) and Additive Constant (C) or (f+d) of a given Tacheometer, using field observations.

Theory:Horizontal and Vertical distances between the stations are determined from tachometric observations, where in measurements either by chain or tape are completely eliminated. The calculations are based on the principle of Isosceles triangles, which states “In Isosceles Triangles, the ratio of the perpendiculars from the vertex on their bases and their bases in constant”.

S1 S2 S3

O A1 A2 A3

D1

D2

D3


PROCEDURE:a) Select a fairly level ground set up the tacheometer on station ‘O’ and complete all the

temporary adjustment.

b) Measure a line OA3 on a straight line, 60 m long and fix the pegs, A1, A2 and A3 at 20 m apart.

c) With line of collimation horizontal hold to staff vertical over station A1 take the stadia hair readings (top and bottom hair readings). Let the Intercept being S1.

d) Similarly the staff intercepts A2 and A3 be taken. Let the intercepts being S2 and S3

respectively.

Observations & Tabulations:

Instrument Station

Staff reading

onDistance (mt)

Stadia readings Staff Intercept (Upper - Lower)

SL& SU

Lower Middle Upper

Caculation:

D=ks+c

Result: The tacheometric constants of the given instrument are -------------


Experiment No: 8 (a) Date :

SETTING OUT OF A SIMPLE CIRCULAR CURVE BY USING CHAIN &TAPE METHOD (PERPENDICULAR OFFSETS FROM TANGETNS)

Aim: Set out of a simple circular curve in the field using chain and tape by the method of perpendicular offsets erected from Tangents.

Apparatus: Chain, Tape, arrows, ranging rods, Cross staff

Objective: Set out of a simple circular curve in the field using chain and Tape by the method of perpendicular offsets erected from Tangents.

Theory: In a simple circular curve offsets are erected perpendicular to Tangents and the toe points of the offsets are joined. This will give the required curve.

P1, P2, P3…………. P11, P2

1, P31 ……………are the toe points of offsets drawn to Tangents T1I

and T2I.

For the given R, deflection angle ∆ , distance of offset from T1\ 26.794 Tangent length, offset values are calculated.

Tangent length, T1I or T2I = R Tan ∆/2, offset value = R-R2 – X2 (perpendicular offsets)Length of Tangent =

X value

Ox

Ox also calculated by approximating as Ox ~ x2 (radial offsets)

2R

Procedure:a) Before starting the field set up of values, calculations are done for Tangent length (26.79 T 1I/ T2I) and offset values OX1, OX2, ………Oxn.

b) The tangents T1I and T2I are set up by prolonging the AT1 line and positioning the chain making an intersecting angle of (180-∆) with T1I.


c) Now the offsets Ox1, Ox2, Ox3 …………are erected perpendicular to the Tangent T1I at x1, x2, x3 ………. Distances from T1 and the toe points of offsets P1, P2, P3…………. are marked by fixing arrows.d) Similarly offsets are erected to the tangent T2I calling the toe points as P1

1, P21, P3

1……….. till the curve is closed.e) By joining all these points P1, P2, P3 ……. P1

1, P21, P3

1 ……. we will get the required simple circular curve.

Check: The value of mid-ordinate measured in the field should be equal to the calculated value. The calculated value is R(1-cos ∆/2). Otherwise check the entire setup..Result: Thus a simple curve is plotted by method of perpendicular offsets from tangents


Experiment No: 8 (b)

SETTING OUT SIMPLE CURVE BY ORDINATES OR OFFSETS FROM LONG CHORD

Aim: To set out a simple curve by ordinates or offsets from long chord.

Equipment used: Chain, Tape, arrows, ranging rods.

Objective: To set out a simple curve by ordinates or offsets from long chord.

Theory: The lengths of the ordinates from the long chord are calculated using the formula.

______ Ox = √R2 - X2 – [R-Oo]

Where Ox = ordinate at a distance x from the mid-point of the chord.R = Radius of the curveOo = Mid ordinate

Mid ordinate can be calculated using the formula

______ O0 = R- √R2 – (L/2)2

Where L = Length of the long chord actually measured the ground.

Procedure: a) Set the long chord on the ground with the help of a chainb) To set out the curve, the long chord is divided into an even number of equal parts.c) Offsets are then calculated from equation (i) (Refer table given below for calculations)d) The calculated offsets are then set out at each interval and pegs are driven at their points.e) Then the points are joined to obtain the required curve on the ground.f) I, should be clearly noted that the distance x in this method is measured from the mid point of the chord.


Table:R = Ø = Length of long chord = 2 R Sin Ø /2

Distance from the mid point of long chord x in m Ordinate Ox

Ox = √R2 - X2 Ox = √ R2-L z 2D

RESULT:The calculated offsets are set on the ground and the required curve is observed.


Experiment No: 8 (c ) Date :

SETTING OUT SIMPLE CURVE BY SINGLE THEODOLITE METHOD

Aim: To set out a simple circular curve using one theodolite and chain/ tape.

Equipment used:Transit Theodolite, Chain, Tape, Arrows, Pegs.

Objectives of the Practical: To set out a simple circular curve using one theodolite and a chain/tape.

Theory: It is an instrumental method of setting a simple circular curve. Theodolite is used for making angular observations, chain/ tape is used for making linear measurements. A Rakine’s tangential angle (δ) is the angle made by any chord with the tangent at the first point of that chord. The total tangential angle (∆) of the any point on the curve in the angle made by the chord joining that point and the first tangent point (T1) with the rear tangent. The total tangential angle of whole arc will be equal to half of the deflection angle (Ø/2) of the arc.

Tangential angle of nth chord, δ n =

Where Cn = Length of nth chord Ф =

R = Radius of the curve =

Total tangential angle of nth chord, interval =

∆n = δ 1 + δ 2 +δ 3 -------+δ n

Note: Tangential angles, deflection angles, Rankines tangential angles and Rankines deflection angle are one and the same.

Equipment used:The following equipment is required to conduct the field work.

1. Transit theodolite2. Chain (20 m. or 30 m.)3. Tape4. Arrows5. Pegs


Procedure of setting out the curve:1. Set the theodolite at the point of curve (T1), with both plates clamped to zero, direct the

theodolite to bisect the point of intersection (B). The line of sight is thus in the direction of the rear tangent (T1B).

2. Release the upper plate end set angle ∆1 on the vernier of theodolite. The line of sight is thus directed along the chord ‘T.M’.

3. With the zero and of the tape at ‘T1’ and an arrow held at a distance T1M = c along it with chain/ tape, swing the tape around T1 till the arrow is bisected by the crosshairs. Thus the first point ‘M’ is fixed.

4. Set the second deflection angle ‘∆2’ on the vernier so that the line of sight is directed along ‘T1N’.

5. With the zero end of the tape at M, and an arrow held at a distance MN=C along it, swing the tape around ‘M’ till the arrow is bisected by the cross-hairs, thus fixing the point ‘N’.

6. Repeat steps (4) and (5) till the last point ‘T2’ is reached.

Check: The last point ‘T2’ thus located must coincide with the previously located tangent point T2. If the discrepancy is small, last few pegs may be adjusted. If it is more, the whole curve should be reset.

Inst.at

Sight to

ChordLength

, CTangential angle, δ Total tangential

angle∆Theodolite

readingRemarks

m 0 ‘ “ 0 ‘ “ 0 ‘ “

Result:

The required curve is set out on the field by this one theodolite + chain / tape method, which can be observed on the field.

EXPERIMENT NO: 8 (d) Date :


SETTING OF SIMPLE CIRCULAR CURVE USING TWO THEODOLITIES

Aim:To set out a simple circular curve using two theodolites.

Equipment used:Transit Theodolite, Ranging rods, Pegs, Chain.

Objectives of the Practical:

To set out a simple circular curve using two theodolites.

Theory:In this method two theodolite are used, one at P.C. and the other at P.T. The method is

based on the principle that the angle between the tangent and the chord is equal to the angle which that chord subtends in the opposite segment.

Equipment used:The following equipment is required to conduct the field work.1. Transit theodolites – 2 Nos.2. Ranging rod(s)3. Pegs4. Chain (20m or 30 m)

Tabulations:

Inst.at

Sight to

ChordLength,

CTangential angle, δ Total tangential

angle∆Theodolite

readingRe

Marks

M 0 ‘ “ 0 ‘ “ 0 ‘ “

Procedure of setting out the curve:


1. Set up one theodolite over T1 (T.P) and the other over T2 exactly and level them accurately.

2. Set the vernier-‘A’ of both instruments to Oo O’ O”.

3. Turn the instrument T1 about the outer axis and bisect the point B, accurately.

4. Turn the instrument T2 about the outer axis and bisect the point T, accurately.

5. Set the vernier ‘A’ of both instruments to the first total tangential angle, ∆1. Now the instrument at T1 is directed along T1 M and that at T2 along T2M.

6. Direct an assist and with a ranging rod, simultaneously viewing through both telescopes to locate the point M and drive a peg there.

7. Next set vernier – A of both instruments to read the second total tangential angle, ∆2. Locate the next peg at N as done in previous step.

8. Locate all other points on the curve by repeating the above procedure.

After setting vernier ‘A’ of both the transits at T1 and T2 to the total deflection angle or Ø/2, the lines of sight should bisect the already located points T2 and B respectively. If there is any error on T2 or B and if it is within the permissible limits, the last few pegs may adjusted. Otherwise, the entire work must be repeated again.

Result: The required curve is set out in the field by using two theodolite method, which can be

observed in the field.



CALCULATION OF AREA BY USING TOTAL STATION

Aim: To find out the area of a given land portion by using total station.Apparatus (or) equipment:

1. Tripod stand2. Total station3. Prism4. Prism rod5. Pegs6. Ranging rods

Procedure:1. Fix the ranging rods at the boundaries of the given area.2. Fix the instrument station on the tripod stand & do the levelling & centering3. Levelling should be done by any tripod screws. First turn the level tube and adjust the

bubbles in centre by using these screws and turn the level tube perpendicular to the these two screws and centre by using third screw to check the level tube is in centre in any direction.

4. Focusing the telescope towards plain wall and by using focusing screw adjusting the eye piece until the cross hairs are clearly visible.

5. Measure the co-ordinates of all the boundary points and save them in the internal memory.

6. From mode A screen press F5(MODE)7. Press F1(SFUNC)8. Press F5(PAGE) one time.9. Press F2 (CALC)10. Select 2D surface & area.11. From the screen select the points measured on the boundary by pressing ENT and press

down arrow F4 again press ENT. While selecting the points all the points are to be selected in order as they are on the ground.

12. After completion of selection of points press F2 (ACCEPT).13. The area will be displayed on the screen of total station.

Result:Calculated area of a given site by using total station = perimeter of the site.

Point Code N E Z


EXPERIMENT :10 Date:

TRAVERSING USING TOTAL STATION

This function allows you the fixed. Closed and open traverse calculations.You can measure not only the corner points but also the side shot points at the same time.

When the traverse is closed, the closing errors of coordinates are calculated and the corner points can be adjusted. And the side shot points from the corner point based on the adjusted each corner point’s coordinates are calculated.

Open point of the traverse data uses the memory size of two or three coordinates data. And therefore please confirm the remaining memory. The calculate types is the compass rule.

The traverse function can store the polar coordinates data and the rectangular coordinates data. And it can send the polar data by DC1 or AUX format and rectangular data or CSV format respectively.


The following assumptions are made:

The current station is the foresight point of the previous station.

The back sight point of current station is the previous station.

The following limitations are made. More than one traverse rout can’t be measured at the traverse same time. Don’t store the other data while you are measuring the traverse route.

When one traverse route is finished, perform the traverse calculation before you store the other data.

Don’s turn the power supply off until the measurement at one start at one corner point is completed.

Don’t escape from the MEASURE screen, too. You can’t use the same PN in one job. And you can’t overwrite the PN in the traverse. The same traverse rout can’t be calculated again. Polar coordinates data of back sight and station points can’t be seen in the POLAR EDIT

function But is sent properly is SEND POLAR DATA function.

Traverse

1) Switch on the instrument center it and level it.2) Press MODE(F5)3) Press SFUN(F1)4) Press File(F1), select CREATE, press ENT, Input file name, press ENT, press ESC.5) Press MEAS(F2), Select RECT COORDINATE, Press ENT.6) STATION press ENT, PN press ENT, change input mode to ABC by pressing F5 button.7) Feed PN, press ENT, press down arrow F4, press ENT.8) Input N, E, Z and HI(Height of instrument – Z and height of instrument is required if we

needed to measure Elevation other wise it is not required to feed the Z and Height of instrument), If required input PC(Point code) press ENT, press SAVE(F1), press ACCEPT(F5).


1. Rectangular co-ordinate measurement. 2. Polar co-ordinate measurement.

At new place where we don’t have coordinates of back sight point direct the telescope towards north press 0 set(F3) two times, press ENT.10)Now you will be in measure screen, if you require Z value(RL) press EDIT(F4), select PH(Prism height), input prism height, and press ENT two times.11)Now hold the prism where you want to measure coordinates, sight the prism, press MEAS(F1), the coordinates will be displayed on the screen, press SAVE(F2) to save the value.

AT CHANGE POINT:1) Measure the foresight point to which we want to shift the instrument, note down The PN

of that point.2) Switch off the instrument, shift the instrument to the next station point, switch on the

instrument, center it and level it.3) Press ESC OR LASER OR ENTbutton(For R400N series).4) Press MODE(F5)5) Press S.FUN(F1)6) Press MEAS(F2)7) Press ENT on Rectangular Measurement Coordinate8) Press ENT on station9) Select PN and press ENT.10) Input the point number on which instrument was set up now andpressENT11) Select IH,

measure and input instrument height press ENT two times, Press ACCEPT(F5)12)PressBSP(F5)13)SelectPN, Press ENT, input the point number of the point to which we are back sighting the instrument, press ENT, Press ACCEPT(F5)14)A message “AIM the reference point and press ENT when ready” will be displayed on thescreen, bisect the back sight point and press ENT.15)Now continue to measuring and saving the next foresight points16)Repeat the procedure at next shift of the instrument.

1.1.


1. PN : X X2. N : X XXXXXXXXX .X XX3. E : X XXXXXXXXX .X XX4. Z : X XXXX .X XX5. PC : 5. OPEN CALC

MEASURE

EXPERIMENT: 11 Date :

REMOTE DISTANCE MEASUREMENT

With RDM measurement, the Horizontal, vertical and slope distance and % of slope between the reference point and the target point are measured. The distance between target 1 and target 2 are also measured any target point can be changed to the new reference point.From the power Topolite screen, press [F5][PAGE] two and press [F4][RDM] .Press [F4][EDIT] select PH and input the prism height press ENT two times.Place the prism at Reference point.Aim at the references point and press [F1][MEAS] to measure the reference point it turn to TARTGET POINT screen automatically.

Aim at the target 1 and press [F1][MEAS] to measure a distance. The distance between reference point and target point 1 is displayed.

V.dst. and % grade are displayed by minus mark when the target point is lower position. Press the [F3][DATA] to view the TARGET POINT screen.


Aim at the target 2 and press [F1][MEAS] to measure a distance. The distance between reference point and target point 2 is displayed.

Press[F5][DISP] to displayed the target distance.

Result:

EXPERIMENT: 12 Date:


CALCULATION OF HEIGHT BY USING TOTAL STATIONAim: To calculate height of given object by using total station.Apparatus: Total Station

Tape Tripod

Procedure: Fix the tripod stand on ground & place the total station on it and approximate levelling

should be done by eye adjustment. Levelling should be done by using screws & bubble should be in centre in dry direction

to turn the telescope.

To calculate the height of the tower we will use this programmer.1. Switch on the instrument level it.2. Place the prism at the bottom of pole to which we want to calculate the height.3. In the instrument press F5(MODE) then press F1(SFUNC), press F5 (PAGE) one time.

Press F2(CALC). Select REM and press ENT.4. Press F4 (EDIT), select PH and press ENT. Input prism height) and press ENT two times.5. Sight the prism and measure it.6. After completion of measurement press ENT. At the bottom the horizontal distance will

be changed to REM.7. Turn the telescope vertically to the top and sight the top point of the tower. 8. Opposite to REM we can see the height of the tower.

Result:Height of the object is


surveying laboratory (1)

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